The present invention relates generally to welding systems and, more particularly, to a stud welder having an inverter power source.
Stud welding is a welding process that utilizes a localized burst of current between a metallic fastener and a metallic work piece. In most instances, although not required, the fastener and the work piece have the same material properties. The fasteners are held and welded in place through the use of an electromechanical device know as a stud gun. A stud welding system has a power source, a stud gun, a pair of cables, and a stud.
Stud welding has applications in many industries. These industries include boiler manufacturing, ship building, auto manufacturing, and construction to name but a few. The work environment in each of these trades is often polluted with dust, dirt, and debris and heavily congested with other equipment and tools. Any equipment operated under these conditions preferably should be designed with these conditions in mind in order to allow easy transport and to extend the life cycle of the equipment.
Stud welder power sources are required to generate and discharge a high current output in a short period of time. Many stud welder power supplies are either manually operated or operated by other equipment such as robotic arms. In order to maintain the quality of the stud weld and maintain operating efficiencies, stud welder power sources need to be both durable and reliable such that the device can produce repeatable results regardless of the method of operation.
Power sources used for stud welding generally provide a constant current. This constant current is generally provided by controlled release of a capacitive discharge or a transformer rectifier. Stud welder power sources that are of the transformer rectifier type are generally iron core based. The majority of stud welder power sources have an iron core base. As with all iron core based power sources, a design consideration involves the logistics and accessibility of the power source. Due to the power output requirements demanded of stud welders, the stud welder power sources are generally large, bulky, and heavy. Such a construction produces limitations on both portability and accessibility of the stud welding power source.
Known stud and stick welders have power sources that typically use silicon-controlled rectifiers (SCRs) to control the welder output. The SCRs are controlled by a circuit board and rectify and control the welder output. These systems provide fewer moving parts than mechanical control systems, such as a brush or tap controlled transformers, and can be remotely controlled. These systems also provide signal control over input power fluctuations such that the fluctuations minimally effect the welder output. Unfortunately, these systems have a limited switching speed, are often challenging to troubleshoot and repair, and are only marginally lighter than mechanically controlled power sources.
Another type of power source is commonly known as an inverter power source. Inverter power sources first rectify incoming power to a direct current. This signal is then filtered for smoothness and sent through power switches that convert the signal back to AC, but at an increased frequency. A transformer steps-down the signal prior to the signal being rectified a second time to DC current. The inverter power source produces a relatively smooth current output, but heretofore, not sufficiently high enough, nor fast enough for stud welding.
Therefore, it would be desirable to have system that allows for a light weight power source to generate an electrical signal capable of welding a stud to a work piece in a quick and repeatable manner. Additionally, the stud welder power source should also be robust and durable.